he Israeli Cabinet met in emergency session today and reportedly decided to react cautiously to the ambush yesterday of an Israeli Army bus east of Beirut that left six soldiers dead and 22 wounded.

The state-run Israeli radio, quoting "official sources," said the Cabinet had decided to downplay the significance of the ambush and was not in this instance blaming Syria for the attack by gunmen. Israeli radio has blamed Palestinian guerrillas for the attack, but no group has claimed responsibility and the gunmen have not been identified. Palestinian guerrillas, however, have previously carried out several ambushes and laid mines on roads in areas occupied by Israel in southern and eastern Lebanon.

The Cabinet met in its capacity as the country's ministerial defense committee, a device designed to prevent leaks of its deliberations, and no official announcement of its decisions was made.

However, a short time after the meeting, Israeli Air Force jets destroyed a Syrian SA9 surface-to-air missile battery in eastern Lebanon.

"The state of Israel is determined not to allow the Syrians to bring surface-to-air missiles into Lebanon," the military command declared in announcing the air attack.

The destruction of the missile battery was a clear reminder to Syria that its forces in Lebanon remain extremely vulnerable to the Israeli Air Force in the event of future attacks on Israeli soldiers. But the announcement of the attack on the missile battery did not connect it with the ambush and it remained unclear whether Israel planned any further military steps.

Israel has said repeatedly that it will hold Syria responsible for actions against its troops in Lebanon by Palestinian guerrillas operating from behind Syrian lines. The ambush produced the highest number of Israeli casualties since the Palestine Liberation Organization forces withdrew from Beirut.

Israel is still reeling from the massacre of Palestinian refugees in West Beirut, which has produced demands here for an Israeli withdrawal from Lebanon, and that may have tempered the government's reaction.

The fact that the Cabinet was called into emergency session to deal with the ambush was an indication that Prime Minister Menachem Begin was adopting a more cautious approach since the massacre. In previous instances of attacks on Israeli troops, Begin and Defense Minister Ariel Sharon have ordered retaliatory steps on their own.

But the massacre has shaken and divided the Begin government and clearly increased the mistrust of Sharon among his Cabinet colleagues, who are demanding that they be consulted more frequently on military matters.

The Tel Aviv daily Yediot Aharonoth said today that 260 Army officers signed a petition calling for Sharon's resignation, The Associated Press reported. The petition cited a "crisis of confidence" between the Army high command and Sharon. The military command and the Defense Ministry had no immediate comment on the report.

Yesterday's ambush and today's air strike broke a lull in the fighting along the line that separates Israeli troops from the Syrian forces and Palestinian guerrillas in central and eastern Lebanon. It is also likely to complicate the task of arranging an agreement for the mutual withdrawal of those forces from Lebanon.

American officials are known to believe that the best hope for gaining a withdrawal lies in an immediate push for an agreement before too many more sporadic incidents of fighting harden attitudes in Jerusalem and Damascus. As part of that diplomatic effort, U.S. envoy Morris Draper arrived in Israel today and is to meet with Begin and other senior officials Tuesday.

Israeli officials said they assumed that Draper was bringing with him the results of U.S. special envoy Philip C. Habib's meetings last week with Syrian officials.

"The Americans seem to be convinced that Syria is ready to withdraw and that what is left is working out the details and timetables," one official said.

But the official said that Israel has not received any confirmation of press reports from Beirut and Damascus that Syria has agreed to a three-stage withdrawal of Syrian and Israeli troops proposed by the United States.